(1 point) A dump truck dumps gravel, forming a conical pile. The volume of the pile increases at a rate of 7 cubic feet per second. The height of the cone is related to the radius by h = 2r. The volume of the cone is given by V = 1/3athr2. Find the rate of change of the radius of the cone when the radius is 10 feet. The radius is changing at feet per second. Find the rate of change of the radius of the cone when the radius is 22 feet. The radius is changing at feet per second